Preparation of viscous polymers



nited St tCS This invention relates to the preparation of viscous polymers and more particularly concerns a process for polymerizing alpha-monoolefin hydrocarbons having three or more carbon atoms per molecule to form viscous oily polymers which have utility as additives for other oils or as lubricants per se.

In the polymerization of alpha-monoolefins which have four or more carbon atoms per molecule, those in which there is a substituent at the beta position generally are more easily polymerized than straight chain monoolefins or than those which have one or more substituents located other than at the beta position. The present invention is directed to the catalytic polymerization of the more diiricultly polymerizable alpha-monoolefins, i.e. those which do not have a substituent at the beta position, for the purpose of producing viscous oily products.

According to the invention, alpha-monoolefins having the formula H H RC=CH wherein R is an alkyl radical having 2-8 carbon atoms, are polymerized by contacting with a dispersion of parti- .cles of a mercury halide in combination with an alkyl aluminum dihalide in an inert organic liquid medium. It has now been found that such dispersions are highly effective catalytic systems for polymerizing the specified monoolefins, or mixtures thereof, to viscous oily products.

In preparing the catalyst system of the present invention a mercury halide, which can be either a mercurous or mercuric halide such as HgCl, HgCI HgF, HgF HgBr or HgI, is dispersed in finely divided anhydrous form in an organic liquid reaction medium and monoalkyl aluminum dihalide, e.g. ethyl aluminum dichloride, is added thereto. Any organic liquid which will be inert under the reaction conditions can be used. Preferably, hydrocarbon liquids are employed, for example, hexanes, heptanes, octanes, cyclopentanes, cyclohexanes, benzene, toluene, xylenes, Decalin and the like. Non-terminal olefins which will not react under the conditions employed during the reaction can also be used.

The aluminum compound employed in the foregoing catalyst system can be any monoalkyl aluminum dihalide wherein the alkyl group has 110 carbon atoms. The preferred compound is ethyl aluminum dichloride; however, its fluorine, bromine, or iodine analogues can be used with good results. Other alkyl radicals can be substituted for the ethyl group, for example, methyl, propyl, isobutyl, isooctyl or decyl radicals.

The polymerization reaction is carried out by contac"- ing the above-described catalyst system with the monomeric olefin which can be introduced into the reaction vessel in either vapor or liquid form. The temperature of the system generally should be above C. and may be as high as 150 C. or even higher. As a general rule the rate of polymerization increases as the reaction temperature is increased. The reaction can be conducted under atmospheric pressure if the boiling point of the reaction medium is above the reaction temperature employed, or an elevated pressure can be employed when the reaction temperature is above the normal boiling point of the reaction medium. If the monomeric olefin charge is a normally gaseous olefin, it is advantageous to maintain an elevated pressure in the reactor since this intut ice

creases the concentration of dissolved olefin in the reaction mixture and results in an increase in reaction rate. During the course of the reaction it is desirable to stir the reaction mixture continuously in order to effect efficient contact between the reactant and the catalyst particles.

In preparing the reaction mixture the proportions of components can be varied widely, and the rate of reaction will depend to an extent on the proportions selected. As a general rule, it is desirable to use a volume ratio of the charge olefin to reaction medium in the range of 0.2 to 5 on a liquid basis. It is also desirable that the molar ratio of mercury halide to the charge olefin be in the range of 0.0001 to 0.05 and more prefer-ably 0.001 to 0.01, and that the molar ratio of the aluminum compound to the mercury halide be in the range of 0J1 to 10 and more preferably 0.2 to 5. The reaction temperature selected will depend to an extent upon the particular olefin to be polymerized but generally will be in the range of 0 to 150 C. and more preferably 50 to C.

The above-described procedure results in the formation of viscous oily polymers which may or may not remain dissolved in the reaction medium depending upon the experimental conditions and the particular monomer used. Upon completing the reaction a polar compound such as methanol is added to the reaction mixture to deactivate the catalyst system. The oily polymer product can be separated from the catalyst and reaction medium by filtration, extraction and/ or distillation. The resulting product can be utilized as a lubricant or can be used to thicken other oils and improve viscosity index. -It can also be blended with other materials, for example, petroleum wax, to impart desirable characteristics. The products of the invention can, if desired, be hydrogenated before final use in order to eliminate terminal unsaturation.

The [following examples illustrate the invention more specifically:

Example I An inert reaction medium consisting of n-heptane .was charged to a reaction vessel and finely divided anhydrous HgCl was added thereto in a molar proportion of one part to 100 par-ts of the hereinafter specified olefin monomer. Ethyl aluminum dichloride was then added to the mixture in a molar proportion .to the HgCl of 3:1. The mixture was heated while being stirred until a temperature of 50 C. was reached. The charge olefin, 4-methylpentene-l, was then added in a volume amount equivalent to the n-heptane and the mixture was stirred for 24 hours with the temperature being maintained at about 50 C. Methanol was then added, the mixture was filtered to separate catalyst particles and the filtrate was distilled to remove the n-heptane and methanol. A viscous oily product was obtained in a yield of roughly 40% by weight based on the 4-methylpentene-l charged to the system.

\A higher yield of viscous polymer product can be obtained by operating in the above manner but employing a higher reaction temperature, e.g. by employing a temperature of 100 C. while maintaining the system under pressure.

Example II The process of Example I was repeated except that HgCl was used in place of HgCl and a viscous oily polymer was obtained in about the same yield.

Example III The process of Example I was repeated, except that the mercuric chloride was deposited on alumina in a ratio of one part of HgCl to nine parts of alumina. After 24 hours, about 50 parts of viscous polymer were obtained.

By way of comparison, when any of the mercury halides is employed in combination with aluminum triethyl in place of ethyl aluminum dichloride, substantially no polymerization of the 4-methylpentene-1 is obtained.

The polymerization of other alpha-olefins having 4;10 carbon atoms and which do not have any substituent in the beta position can be carried out in the manner above described with substantially similar results. For example, alpha-olefins such as .butene-l, 3-methylbutene-l, 3-

EthYl bUtGIlE-ll, pentene-l, hexene-L, 4-methylpentene-l, 3,4-dimethylpentene-1, octenel, vinylcyclohexane, 4,4- dimethylpent'ene-l, decene-l and 5-ethyl-4,4-dimethylhexene-l can be polymerized in accordance with the invention to yield viscous oily polymers.

This application is a continuation-in-part of my copending application Serial No. 773,164, filed November 12, 1958, now abandoned.

I claim:

1. Polymerization method for forming viscous polymers which comprises contacting 4-methylpentene-l, under polymerizing conditions including a temperature in the range of 0-150 C., with a dispersion in an inert organic liquid medium of a mercury halide in combination with an alkyl aluminum dihalide, the molar ratio of alkyl aluminum dihalide to mercury halide being in the range of 011 to 10.

2. Method according to claim 1 wherein the alkyl aluminum dihalide is ethyl aluminum dichloride.

References Cited in the file of this patent UNITED STATES PATENTS 2935.542 Minckler et a1 May 3, 1960 

1. POLYMERIZATION METHOD FOR FORMING VISCOUS POLYMERS WHICH COMPRISES CONTACTING 4-METHYLPENTENE-1, UNDER POLYMERIZING CONDITIONS INCLUDING A TEMPERATURE IN THE RANGE OF 0-150* C., WITH A DISPERSION IN AN INERT ORGANIC LIQUID MEDIUM OF A MERCURY HALIDE IN COMBINATION WITH AN ALKYL ALUMINUM DIHALIDE, THE MOLAR RATIO OF ALKYL ALUMINUM DIHALIDE TO MERCURY HALIDE BEING IN THE RANGE OF 0.1 TO
 10. 